A large grocery store is attempting to staff its check-out registers. Currently, the arrival rate is 1 = 320 customers per hour, each server has a service time of E IT = 3.75 minutes on average, and the interarrival and service times follow an exponential distribution. 1. Considering any one of the individual s' queues, derive the expected number of customers waiting in line. a. 8.1 customers b. 3.2 customers c. 2.25 customers d. 0.9 customers 2. For any one of the individual s' queues, what is the expected waiting time (minutes) spent in line for a customer? O a. 15 minutes b. 38 minutes c. 10 minutes O d. 4 minutes 3. Considering any one of the individual s queues, derive the expected expected number of customers in the system (waiting plus service). a. 3 customers b. 4 customers c. 1.5 customers D. 9 customers